Acoustical characterization of clay pots in Ottoman architecture through experimental and numerical analysis methods

Employment of clay pots as building elements is a common practice especially in the medieval structures throughout Europe and Near East. Despite the fact that their acoustical employment in historic structures is well known and dates back to the 1st century BC as observed in Vitruvius' writings, their true contribution to the acoustics of Medieval Architecture remains to be a subject of discussion. They are also present in Ottoman Architecture including Süleymaniye Mosque designed by Sinan the Architect Laureate. Although these elements placed in the dome of Süleymaniye are often interpreted to be utilized as Helmholtz resonators, a scientific account regarding their sound-absorption performance is needed so as to understand whether they actually perform as cavity resonators. Therefore, the scientific investigation of their acoustical behaviour through analytical, experimental, and numerical analysis methods is necessitated. The objective of this study is to discuss the effects of the clay pots on the sound energy decay pattern of Süleymaniye Mosque. The study begins with an archival research phase covering the versatile employments of clay pots as building elements that are not limited to their acoustical utilization. The study then proceeds with the impedance tube measurements conducted with the reproduced sample of an actual-sized clay pot employed in the structure. The results are then verified with finite element modelling (FEM) simulations. Finally, sound absorption coefficients, obtained from the latter are transferred into the ray tracing simulations so as to understand the pots' effect on reverberation times (T30) in the edifice. In the conclusion part, sound absorption performance of clay pots and their possible contribution to the mosque acoustics are discussed. As a result of the study, the resonance frequency of the clay pots embedded into the central dome of Süleymaniye Mosque is found to be 50 Hz. Additionally, they are also proven to be effective at 500 Hz octave band. Consequently, the ray tracing simulations exhibit a 2 seconds decrease in T30 values at 500 Hz octave band. This also proves the improvement of reverberation time at this octave band range, which was measured after the final restorations of Süleymaniye Mosque with repaired pots.